MATE Transporter Facilitates Bitter Saponin Transport from Cytoplasm to Vacuole

Domestic soybeans serve as a vital source of healthy edible plant oil and high-quality plant protein in our dietary culture. In addition to the well-known components of oil (approximately 20%), protein (approximately 40%), and carbohydrates (approximately 30%), soybean seeds also contain a range of specialized metabolites that promote human health. For instance, soyasaponins, comprising 0.5-6.5% of the seed, and isoflavonoids, comprising 0.01-0.5%, are crucial for promoting human health.

 

Particularly, soyasaponins, belonging to the oleanane-type triterpenes, directly affect the health and taste quality of soybeans depending on their content and proportion. Currently, although genes involved in soyasaponin synthesis have been well-investigated, genes related to the accumulation and transport of soyasaponins are largely unknown.

 

The research team led by Dr. Guodong Wang from Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, utilized gene co-expression analysis to identify GmMATE100 from 117 members of the MATE (Multidrug and toxic compound extrusion) transporter family in the soybean genome as a candidate gene for soyasaponin transport.

 

Subcellular localization experiments demonstrated that GmMATE100 is localized to the vacuolar membrane in both plant and yeast cells. In vitro yeast transport assays revealed that GmMATE100 exhibits activity in transporting both type A and type B soyasaponins but is unable to transport the soyasaponin precursor, soyasapogenol (as shown in Figure 1).

 

Using Cas9 technology, they generated GmMATE100 knockout mutants, and LC-MS analysis showed a significant decrease in the content of type A and type B soyasaponins in the roots and seeds of the mutant materials compared to the wild type.

 

Taken together, these results establish GmMATE100 as the first identified soyasaponin transporter responsible for the transport of type A and type B soyasaponins from the cytoplasm to the vacuole. This study provides a new avenue for targeted modification of soyasaponin content and composition in soybean seeds, thereby improving soybean health and taste quality.

 

The research findings, titled "GmMATE100 is involved in the import of soyasaponins A and B into vacuoles in soybean plants (Glycine max L.)," were published in the Journal of Agricultural and Food Chemistry on April 22nd (DOI: 10.1021/acs.jafc.4c01774).

 

The research involved collaboration with Dr. TIAN Zhixi from the Institute of Genetics and Developmental Biology and Prof. YU Fang from Dalian University of Technology. Funding for this research was provided by the National Key Research and Development Program and key deployment projects of the Chinese Academy of Sciences.

 

 

 

Contact:

Dr. WANG Guodong

Institute of Genetics and Developmental Biology, Chinese Academy of Sciences

Email: gdwang@genetics.ac.cn